CN106732621A - Sulfur-resistant catalytic combustion catalyst, and preparation method and application thereof - Google Patents

Abstract

The invention discloses a sulfur-resistant catalytic combustion catalyst, a preparation method and an application. The catalyst uses γ-Al ₂ O ₃ or 5A molecular sieve as a carrier, and copper-cobalt solid solution oxide and cerium oxide, or copper-cobalt solid solution oxide as active components; wherein the active component load mass is the mass of the carrier 10% to 20%, the catalyst is prepared by an ultrasonic-equal volume impregnation method, and the prepared catalyst is suitable for catalytic combustion to eliminate industrial volatile organic waste gas pollution. The catalyst of the invention has certain sulfur resistance in the catalytic combustion of organic waste gas, has the advantages of high activity, high stability, simple preparation method and the like.

Description

A kind of anti-sulfur catalytic combustion catalyst and its preparation method and application

technical field

The invention belongs to the fields of environmental protection catalytic materials and air pollution control, and in particular relates to a sulfur-resistant catalytic combustion catalyst, a preparation method and an application.

Background technique

With the rapid development of the chemical industry, volatile organic compounds (VOCs)-based exhaust emissions not only cause great harm to human health, but also promote the generation of urban photochemical smog and haze, seriously polluting the atmospheric environment. Therefore, the control of volatile organic compounds has attracted the attention of environmental protection departments and enterprises at all levels.

Commonly used VOCs treatment technologies include thermal combustion, catalytic combustion, adsorption, biological treatment, plasma oxidation, and photocatalytic oxidation. Among them, the catalytic combustion method refers to the flameless combustion of organic waste gas at low temperature in the presence of a catalyst to generate harmless substances such as carbon dioxide and water to achieve the purpose of treatment. Catalytic combustion technology has the characteristics of low energy consumption, high combustion efficiency, low ignition temperature and low secondary pollution, and is a widely used VOCs treatment technology. The key to catalytic combustion technology is to select and develop a suitable catalyst.

Patent CN102441404A discloses a sulfur-resistant catalytic combustion catalyst and its preparation method, which solves the problem that the catalyst is prone to sulfur poisoning in the prior art. The catalyst uses noble metal Pt as the active component and honeycomb ceramics as the carrier, wherein the noble metal load is 0.2-3.5g per liter of catalyst, and the active Al ₂ O ₃ is 40%-85% based on the total weight of the coating, TiO ₂ 5%-50%, CeO ₂ 5%-15%, La ₂ O ₃ 2%-10%, one or more of CuO, MnO ₂ , NiO, Fe ₂ O ₃ 3%-15%. However, noble metal catalysts have disadvantages such as few sources, high price, and easy poisoning, which hinder their application.

Based on the above analysis, it is of great practical value to develop a catalyst with low cost, high activity, good sulfur resistance and stability.

Contents of the invention

The object of the present invention is to provide a sulfur-resistant catalytic combustion catalyst with low price, excellent catalytic activity and certain sulfur resistance in view of the shortcomings of the existing noble metal catalysts, which are high in cost and prone to sulfur poisoning. Another object of the present invention is to provide The preparation method of the above-mentioned catalyst, the present invention also aims to provide the application of the above-mentioned catalyst.

The technical scheme of the present invention is as follows: a sulfur-resistant catalytic combustion catalyst, characterized in that: γ-Al ₂ O ₃ or 5A molecular sieve is used as a carrier, copper-cobalt solid solution oxide and cerium oxide, or copper-cobalt solid solution oxide It is an active component; wherein the load mass of the active component is 10% to 20% of the mass of the carrier.

Preferably, the mesh number of the above-mentioned carrier is 16-40 mesh. Preferably, the molar ratio of copper, cobalt and cerium in the above catalyst active components is 1:(1.8-2.1):(0-1.5).

The present invention also provides the preparation method of above-mentioned anti-sulfur catalytic combustion, and its concrete steps are as follows: preparation copper nitrate, cobalt nitrate and cerium nitrate solution, three kinds of nitrate solutions are 1 according to the molar ratio of copper, cobalt and cerium:( 1.8～2.1): (0～1.5) mixed; after the carrier is dried in the oven; add the dried carrier to the prepared mixed solution, ultrasonically stir in the ultrasonic device, and mix well; the resulting mixture is placed in the oven drying in medium temperature; put the dried mixture in a muffle furnace and bake at 500-800°C for 4-5 hours to obtain the anti-sulfur catalytic combustion catalyst.

Preferably, the drying temperature of the above-mentioned carrier in the oven is 100-120° C., and the drying time is 4-6 hours; the drying temperature of the mixture in the oven is 100-120° C., and the drying time is 10-14 hours.

Preferably, the ultrasonic frequency in the ultrasonic device is 20kHz-28kHz, and the stirring time is 0.5-2 hours.

The present invention also provides the application of the above-mentioned anti-sulfur catalytic combustion catalyst in the catalytic combustion treatment of volatile organic waste gas.

Preferably, the above-mentioned volatile organic waste gas is benzene, toluene or xylene.

The catalytic combustion reaction is carried out in a fixed-bed reactor: 10ml of catalyst is placed in the isothermal zone of the reaction tube, and small particles of quartz sand are added above and below the catalyst bed to reduce dead volume. The reactor is a stainless steel tube with an inner diameter of 12 mm and a length of 1000 mm. The electric heating mantle is used for heating and heat preservation. The gas concentration is 4113mg/m ³ , the catalytic combustion reaction temperature is 180°C-420°C, and the reaction tail gas is analyzed by gas chromatography.

Beneficial effect:

The catalyst of the present invention is suitable for catalytic combustion of VOCs and has the following advantages:

1. The catalyst researched and developed by the present invention is used in the catalytic combustion of volatile organic waste gas, which is different from the traditional application of noble metal catalytic combustion catalysts, with non-noble metal oxides as the main active components, and the raw materials are easy to obtain.

2. By loading specific metal elements, under specific conditions, proportioning and optimizing the preparation process, the surface of the catalyst can form solid solutions and rare earth metal oxides, which has a certain resistance to sulfur poisoning and has a high catalytic effect on benzene series such as toluene active.

3. The addition of rare earth elements can also improve the dispersion of the catalyst, and it is not easy to sinter under high temperature conditions, which overcomes the problem that traditional precious metal catalysts are easy to sinter at high temperatures.

Description of drawings

The 10%Cu-Co-O/5A molecular sieve catalyst surface SEM picture that Fig. 1 embodiment 2 makes;

Fig. 2 is the SEM image of the surface of the 20% CeO ₂ /Cu-Co-O/γ-Al ₂ O ₃ catalyst prepared in Example 3.

detailed description

The present invention will be further described in detail below in conjunction with the examples, wherein some preparation conditions are only used as illustrations of typical cases, and are not intended to limit the present invention.

Example 1

The crushed and sieved γ-Al ₂ O ₃ carrier (16-30 mesh) was dried in an oven at 110° C. for 4 hours. Weigh 4.03g Cu(NO ₃ ) ₂ ·3H ₂ O and 9.70g Co(NO ₃ ) ₂ ·6H ₂ O, wherein the atomic ratio of copper to cobalt is 1:2, add a certain amount of deionized water to dissolve and prepare a 25ml solution. Immerse 20g of γ-Al ₂ O ₃ support in equal volume in the above mixed solution, ultrasonically vibrate for 40min at an ultrasonic frequency of 25kHz, dry at 110°C for 13h, and bake at 600°C in a muffle furnace for 5h to obtain a 20% Cu- Co-O/γ-Al ₂ O ₃ catalyst.

Example 2

The crushed and sieved 5A molecular sieve carrier (20-40 mesh) was dried in an oven at 120° C. for 4 hours. Weigh 2.01g Cu(NO ₃ ) ₂ ·3H ₂ O and 4.35g Co(NO ₃ ) ₂ ·6H ₂ O, wherein the copper-cobalt atomic ratio is 1:2, add a certain amount of deionized water to dissolve and prepare a 28ml solution. Immerse 20g of 5A molecular sieve carrier in equal volume in the above mixed solution, ultrasonically vibrate at an ultrasonic frequency of 20kHz for 100min, dry at 110°C for 12h, and bake at 500°C in a muffle furnace for 5h to obtain a 10% Cu-Co-O/ 5A molecular sieve catalyst. The SEM image of the catalyst surface is shown in Figure 1. It can be seen from Figure 1 that the copper oxide and cobalt oxide crystal particles on the surface of the catalyst are small and evenly distributed, and the catalyst still has the original pore structure of the molecular sieve after loading.

Example 3

The crushed and sieved γ-Al ₂ O ₃ carrier (16-30 mesh) was dried in an oven at 110° C. for 6 hours. Weigh 4.03gCu(NO ₃ )2·3H ₂ O, 9.70gCo(NO ₃ ) ₂ ·6H ₂ O, 7.74gCe(NO ₃ ) ₂ ·6H ₂ O, wherein the atomic ratio of copper, cobalt and cerium is 1:2:1 , add a certain amount of deionized water to dissolve, and mix to obtain the active component solution. Immerse 20g of γ-Al2O3 support in equal volume in the above mixed solution, ultrasonically vibrate at an ultrasonic frequency of 28kHz for 35min, dry at 120°C for 10h, and bake in a muffle furnace at 600°C for 5h to obtain a 20% CeO ₂ /Cu- Co-O/γ-Al ₂ O ₃ catalyst. The SEM image of the catalyst surface is shown in Figure 2. It can be seen from Figure 2 that the catalyst still has a porous structure of alumina after loading.

Comparative example 1

The crushed and sieved γ-Al ₂ O ₃ carrier (16-30 mesh) was dried in an oven at 110° C. for 4-6 hours. Weigh 10.85g Co(NO ₃ ) ₂ ·6H2O, add a certain amount of deionized water to dissolve, and mix to obtain an active component solution. Immerse 20g of γ-Al ₂ O ₃ support in equal volume in the above mixed solution, oscillate ultrasonically for 40min, dry at 110°C for 6h, and bake in muffle furnace at 500°C for 4h to obtain a loading capacity of 20% CoO _x /γ- _{Al2 O3} catalyst.

Example 4

The catalytic combustion activity test of the composite oxide catalyst prepared according to Example 3 is carried out in a fixed-bed reactor: 10ml of catalyst is placed in the isothermal zone of the reaction tube, and the upper and lower sides of the catalyst bed are respectively filled with small particles of quartz sand to reduce dead volume. The reactor is a stainless steel tube with an inner diameter of 12 mm and a length of 1000 mm. The electric heating mantle is used for heating and heat preservation. The gas concentration was 4113 mg/m ³ , and the catalytic combustion reaction temperature was 180°C-420°C. The reaction tail gas was analyzed by gas chromatography, and the reaction temperatures at different conversion rates of different organic gases were recorded. The results are shown in Table 1. As can be seen from Table 1, the catalyst prepared by the present invention has higher catalytic activity.

Example 5

The catalyst prepared by the method of the above-mentioned Examples 1-3 and the catalyst prepared by the method of Comparative Example 1 were evaluated by the device described in Example 4 for catalytic combustion of toluene, and the results are shown in Table 2.

Example 6

Catalyst among the example ₃ is used 500ppm, flow velocity is the SO of 1ml/s After 30min, carry out toluene catalytic activity evaluation under the apparatus described in embodiment 4, the result is as table 2.

Table 1 Catalytic combustion activity of various VOCs

Table 2 Catalyst activity evaluation results

It can be seen from the comparison of the above experiments that when the present invention is used for catalytic combustion and purification treatment of volatile organic compounds, the catalyst has relatively high catalytic activity and high thermal stability. The catalyst prepared by the invention has strong practicability, the preparation method adopts an equal-volume impregnation method, the process is simple and environmentally friendly, and the catalyst production cost is low, so it is expected to replace the current industrial precious metal catalyst.

Claims (8)

1. a kind of Sulfur-resistant catalytic combustion catalyst, it is characterised in that：With γ-Al₂O₃Or 5A molecular sieves are carrier, with copper cobalt solid solution Oxide body and cerium oxide, or copper cobalt solid solution, oxide are active component；Wherein active component load quality is load The 10%~20% of weight.

2. Sulfur-resistant catalytic combustion catalyst according to claim 1, it is characterised in that described carrier mesh number is 16~40 Mesh.

3. Sulfur-resistant catalytic combustion catalyst according to claim 1, it is characterised in that in described catalyst activity component The mol ratio of copper, cobalt and cerium is 1：(1.8-2.1)：(0~1.5).

4. a kind of to prepare the method that sulfur resistive catalysis as claimed in claim 1 is burnt, it is comprised the following steps that：Preparation copper nitrate, Cobalt nitrate, cerous nitrate solution, by three kinds of nitrate solutions according to copper cobalt cerium mol ratio be 1：(1.8~2.1)：(0~1.5) mix Close；After carrier is dried in an oven；Dried carrier is added in the mixed liquor prepared, the ultrasound in Vltrasonic device Stirring, is sufficiently mixed uniform；Gained mixture is dried in an oven；Dried mixture is placed in 500 in Muffle furnace~ 800 DEG C are calcined 4~5 hours, obtain final product Sulfur-resistant catalytic combustion catalyst.

5. method according to claim 4, it is characterised in that dry temperature is carrier in an oven

100-120 DEG C, drying time is 4~6 hours；Dry temperature is 100-120 DEG C, drying time to mixture in an oven It is 10-14 hours.

6. method according to claim 4, it is characterised in that the supersonic frequency 20kHz-28kHz in Vltrasonic device, stirring Time is 0.5~2 hour.

7. a kind of Sulfur-resistant catalytic combustion catalyst as claimed in claim 1 is in the catalysis burning treatment of volatile organic waste gas Application.

8. application according to claim 7, it is characterised in that described volatile organic waste gas are benzene, toluene or diformazan Benzene.